Evaluation of Sigma-Delta-over-Fiber for High-Speed Wireless Applications
Doktorsavhandling, 2020

Future mobile communication networks aim to increase the communication speed, provide better reliability and improve the coverage. It needs to achieve all of these enhancements, while the number of users are increasing drastically. As a result, new base-station (BS) architectures where the signal processing is centralized and wireless access is provided through multiple, carefully coordinated remote radio heads are needed. Sigma-delta-over-fiber (SDoF) is a communication technique that can address both requirements and enable very low-complexity, phase coherent remote radio transmission, while transmitting wide-band communication signals with high quality. This thesis investigates the potential and limitations of SDoF communication links as an enabler for future mobile networks.

In the first part of the thesis, an ultra-high-speed SDoF link is realized by using state-of-the-art vertical-cavity surface-emitting-lasers (VCSEL). The effects of VCSEL characteristics on such links in terms of signal quality, energy efficiency and potential lifespan is investigated.
Furthermore, the potential and limitations of UHS-SDoF are evaluated with signals having various parameters. The results show that, low-cost, reliable, energy efficient, high signal quality SDoF links can be formed by using emerging VCSEL technology. Therefore, ultra-high-speed SDoF is a very promising technique for beyond 10~GHz communication systems.

In the second part of the thesis, a multiple-input-multiple-output (MIMO) communication testbed with physically separated antenna elements, distributed-MIMO, is formed by multiple SDoF links. It is shown that the digital up-conversion, performed with a shared local-oscillator/clock at the central unit, provides excellent phase coherency between the physically distributed antenna elements. The proposed testbed demonstrates the advantages of SDoF for realizing distributed MIMO systems and is a powerful tool to perform various communication experiments in real environments.

In general, SDoF is a solution for the downlink of a communication system, i.e. from central unit to remote radio head, however, the low complexity and low cost requirement of the remote radio heads makes it difficult to realize the uplinks of such systems. The third part of this thesis proposes an all-digital solution for realizing complementary uplinks for SDoF systems. The proposed structure is extensively investigated through simulations and measurements and the results demonstrate that it is possible realize all-digital, duplex, optical communication links between central units and remote radio heads.

In summary, the results in this thesis demonstrate the potential of SDoF for wideband, distributed MIMO communication systems and proposes a new architecture for all-digital duplex communication links. Overall, the thesis shows that SDoF technique is powerful technique for emerging and future mobile communication networks, since it enables a centralized structure with low complexity remote radio heads and provides high signal quality.

ultra-high speed communication

energy harvesting

radio frequency (RF)

Sigma-delta-over-fiber (SDoF)


wireless power transfer

1-bit communication

vertical-cavity surface-emitting-laser (VCSEL)


Kollektorn, MC2, (Password for online defence: ICSdefence)
Opponent: Prof. Nuno Borges de Carvalho, Instituto de Telecomunicações, Universidade de Aveiro, Portugal.


Ibrahim Can Sezgin

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik, Mikrovågselektronik

Effect of VCSEL Characteristics on Ultra-High Speed Sigma-Delta-Over-Fiber Communication Links

Journal of Lightwave Technology,; Vol. 37(2019)p. 2109-2119

Artikel i vetenskaplig tidskrift

A Flexible Multi-Gbps Transmitter Using Ultra-High Speed Sigma- Delta-over- Fiber

IEEE MTT-S International Microwave Symposium Digest,; Vol. 2018-June(2018)p. 1195-1198

Paper i proceeding

Evaluation of Distributed MIMO Communication Using a Low-Complexity Sigma-Delta-over-Fiber Testbed

IEEE MTT-S International Microwave Symposium Digest,; Vol. 2019-June(2019)p. 754-757

Paper i proceeding

Evaluation of Simultaneous Wireless Information and Power Transfer with Distributed Antennas

2020 50th European Microwave Conference, EuMC 2020,; (2021)p. 518-521

Paper i proceeding

A Low-Complexity Distributed-MIMO Testbed Based on High-Speed Sigma-Delta-Over-Fiber

IEEE Transactions on Microwave Theory and Techniques,; Vol. 67(2019)p. 2861-2872

Artikel i vetenskaplig tidskrift

I. C. Sezgin, L. Aabel, S. Jacobsson, G. Durusi, Z. H. Se, and C. Fager,”All Digital, Radio-over-Fiber, Time-Division Duplex Communication Link for Distributed Antenna Systems,”


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Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4875


Chalmers tekniska högskola

Kollektorn, MC2, (Password for online defence: ICSdefence)


Opponent: Prof. Nuno Borges de Carvalho, Instituto de Telecomunicações, Universidade de Aveiro, Portugal.

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